1. Field of the Invention
The invention relates to a reducing agent tank for receiving and storing a reducing agent solution, having a filler neck and a fill level sensor for determining the fill level of the reducing agent solution in the reducing agent tank.
2. Detailed Description of the Prior Art
For the reduction of a nitrogen oxide fraction in the exhaust gas of an internal combustion engine, exhaust-gas aftertreatment may be performed using an aqueous reducing agent solution. The aqueous reducing agent solution may be referred to as a reducing agent. The reducing agent is preferably urea. For the exhaust-gas aftertreatment, the aqueous reducing agent solution is pumped, by way of a liquid pump, to a reducing agent injection valve that meters the reducing agent solution into an exhaust-gas flow in an exhaust tract of the internal combustion engine upstream of the SCR catalytic converter. A specially designed reducing agent tank is used to store the reducing agent. A situation may arise in which the reducing agent tank is filled not with the aqueous reducing agent solution but with another liquid, such as fuel or oil. Such misfilling of the reducing agent tank would lead to severe damage to the exhaust-gas aftertreatment system and must be reliably detected in order that relevant protective measures can be initiated. A protective measure after misfilling of the reducing agent tank could be a deactivation of the exhaust-gas aftertreatment system, a corresponding entry in the fault memory of the engine controller, and/or a warning message to the driver of the vehicle.